Question about using multiple graphic cards to rendering
Nvidia has disabled SLI for the 1060.

Blender can make use of multiple gpus that are plugged in but not connected to each other (via corrsfire or SLI or whatever there is).

But there are a few downsides: 
 - the memory of the cards don't add up. as both cards need to store the
   scene information in the memory, the card with less memory is the
   bottleneck
 - you'll have a "dead" card in your setup almost all the time (except when you are actually rendering)